String Theory
by silver-kin
Summary: Something about the way Chris says that—how his tone curls up at the end—gives Tanba pause. "Yuu, what are you up to?"


Notes: Part 3 of the "honeymoon photos" series.

Disclaimer: Diamond no Ace belongs to Terajima Yuuji.

**String Theory**

When Chris slips out of the market crowd with a maroon plastic bag in one hand and a secret glittering in his eyes, Tanba is immediately suspicious. He _knows_ that look, and more importantly, he knows what it _means._

Tanba shifts his weight from foot to foot, waiting for Chris to catch up, before he comments, "Someone looks happy."

He laughs. "I found something nice."

"Oh?" Tanba squints at the bag. "What did you get?"

Chris smiles sweetly at him. "You'll see."

That coupled with the way Chris touches his arm and urges him forward tells Tanba not to ask, at least not now, so he drops the subject. They fall into step together, pointing out lunch options as they walk, shadowed by the afternoon sun and the distant roll of ocean waves.

* * *

It isn't until later, after they get back to the suite and Chris flits to the bathroom with a hasty excuse, that Tanba remembers the mysterious shopping expedition. He looks about the room, and notes that the bag is nowhere to be seen. When he listens, the bathroom is completely silent save for the occasional rustle of plastic.

Tanba crawls into bed, and switches on the television.

He loses track of how much time passes, lulled to sleepiness by the hot sun and the cool breeze sweeping in through the open windows. The curtains dance in the corners, and it's so quiet, even the noise of the television fading into the background—Tanba feels himself slipping away, falling towards a half-doze.

But then the door clicks open, and Chris comes out smiling, and Tanba snaps right back to attention. It's that smile again, and his stomach twists with recognition as Chris pads over to kneel on the bed, chucking the bag from earlier onto the side table.

Tanba sits up a little straighter, and says, "Someone looks _really_ happy."

To his surprise, Chris flushes, gaze flickering away. "Maybe."

"Now will you tell me what you bought?"

Chris licks his lips. "Actually, I think it's better if you see for yourself."

Tanba stares.

A beat passes, and then Chris reaches out to push Tanba back, down against the headboard. Tanba goes willingly, lets Chris nudge his legs aside and so he can slip into his lap. Chris' fingers flutter against Tanba's sides, bordering on the edge of ticklish, and when Tanba wriggles in response, Chris goes rigid.

"Yuu?"

Chris takes Tanba's hands, raises them to his own hips. "Go on," he murmurs, cheeks dusted pink. "Take a look."

He takes the hint, begins moving his palms up Chris' sides, slowly. Tanba keeps his gaze on Chris' face the entire time, watching the way the bloom in his cheeks climb in tandem with his own hands, turning darker every second. It draws Tanba in, mesmerising, until he's leaning past the little space between them, and Chris is softness against his lips, tiny puffs of breath against his jaw.

Chris makes a quiet sound, and Tanba realises he's stopped moving, so he picks up from where he left off. Tanba feels the crests of bone and muscle, and then a single, hard bump, laid between Chris' ribs, one on each side of his chest.

"Yuu," he hums, "what are you wearing?"

By now Chris' breath is coming a little fast, his lips parted ever so slightly. The corners of his mouth quirk up, and he says, "I told you. See for yourself."

So he catches the hem of Chris' shirt, tugs it up and over his head, and tosses it away. Chris rolls his shoulders back, tucks his chin in and slants a heavy-lidded gaze his way. Tanba stares.

He _stares._

Neither of them move. The minutes drag on, agonisingly slow, until Chris shifts in place, and clears his throat. "Well?"

"God, Yuu," he breathes.

Chris ducks his head, and Tanba has enough presence of mind left to register how hard he's blushing, how red the tips of his ears are, before Chris snatches up his wrists, tugging his attention back to where he wants it.

Tanba tracks the line of string laid bare against Chris' skin, traces the outline of red fabric stretched across Chris' chest. He follows the cloth as it thins out into strings, up to where it disappears behind Chris' neck, tucked away in what feels like a frill of ribbons.

"I was definitely not expecting this," Tanba admits.

Chris peers at him. "Really? What were you expecting then?"

But Tanba can only shake his head, because Chris is sitting in his lap, shirtless and bare save for the—the _bikini._ He's wearing a _bikini,_ of all things.

Chris shifts again, purposeful. "Like what you see?"

"Yes," he replies. "Yes. You look—you look _good."_

That lights up his expression brighter than any sun Tanba's ever seen. "Good," he says, leaning forward until their lips are brushing, voice dropping to a low whisper. "Because there's more."

And this time Tanba doesn't need any hints or encouragement; he's diving for Chris' trousers immediately, popping the button and tugging the zipper down. Their position makes it difficult, but Tanba manages to pull the denim low enough for Chris to kick it the rest of the way off—and there's the second half of Chris' secret purchase: a network of strings cuddling his hipbones, holding up the small, scanty piece of cloth tucked neatly between his legs, barely covering the half-hard cock Tanba can see pressing up against the fabric.

Tanba sucks in a quick breath, lifts his gaze to meet Chris'. "You look _really_ good," he amends.

Chris' cheeks turn scarlet. "You would too."

He scoffs. "No way. I'd never pull this off half as well as you do."

"You won't know until you try."

Something about the way Chris says that—how his tone curls up at the end—gives Tanba pause. "Yuu, what are you up to?"

Chris chews on his lower lip. "Look in the bag."

Tanba turns to the bedside table, stretching to reach the bag. He digs around until he finds it—what is unmistakably it, what can _only_ be it.

When he looks up, Chris is watching him with a tentative expression. "Obviously, you don't have to put it on if you don't want to," he adds. "I was just wondering. I mean. It might be fun. If you wanted to. It's fine if you don't want to. Obviously." He stops, clears his throat again.

Tanba is torn between staring incredulously at Chris, and staring incredulously at the article of clothing he's holding, and staring in general. It's been a while since he's heard Chris ramble like that, and oddly enough, it makes him feel a little better, even as his mind swirls with a mental image he can't really process.

"Kouchirou?" Chris finally says, after the silence stretches on for too long.

Tanba swallows, grips the two piece set a little tighter. "You're gonna have to help me put it on."

* * *

The bottom half is easy enough. _Like underwear,_ Tanba thinks, slipping it on as quickly as possible, _only smaller._

_Much, much smaller._

Tanba straightens, and tries not to fidget as he realises how little it covers. He picks up the top piece, turns it over in his hands, and holds it out to Chris, feeling helpless.

Chris takes it from him. "Turn around," he murmurs.

He does, sitting down on the edge of the bed with his back to Chris. He hears Chris inhale quietly, and then the mattress is shifting around him.

"Lift your arms a bit."

Tanba obeys, and then Chris is leaning forward, arms at Tanba's sides as he slides the top piece over his chest, twisting the ends into a knot.

"Is that too tight?"

"No," he whispers.

He presses lightly on his arms and Tanba drops them. Chris leans forward, reaching around his neck for the remaining strings.

Tanba sucks in a quick breath, hears it echoed near his ear.

This knot takes a little longer, and Chris hovers over Tanba's shoulder, adjusting the bikini so it sits just right, snug over his nipples. His fingers tickle Tanba's nape, and Tanba is on edge enough that he jolts at the contact.

"Cold?" Chris asks.

Tanba shakes his head, doesn't trust his voice enough to speak.

This knot takes a little longer, and every brush of contact has Tanba shivering. He tries to focus on breathing, but he keeps getting distracted by how exposed his ass feels, how cold his thighs are, how the press of cloth over his nipples is making him itch in his own skin, and he has to bite his lip to keep still.

After what seems like an eternity, Chris backs away with a quiet, "Done."

Tanba tries to resist the urge to reach back, and fails. He pats the tiny knot resting on his nape, gingerly, and then he drops his hand, unsure of what to do now.

Chris coughs lightly, sounding every bit as uncertain as Tanba feels. "Turn around?" he asks.

He takes a deep, shaky breath, and releases it. He takes another, and turns to face Chris, keeping his gaze downcast. His whole body twitches with the urge to cover himself; he feels so exposed like this, which is ridiculous given the countless times he's been stark naked around Chris before, but it feels strange, and he must look absolutely ridiculous, not at all like Chris does, and he's seriously starting to regret saying yes to this—

A palm folds over Tanba's cheek, warm, and Chris edges closer. "Hey," he murmurs. "Look at me?"

He grits his teeth, tasting 'no' on his tongue, but he manages a quick glance up, before dropping his gaze back to his lap, and pausing. Because Chris' eyes—

"Told you you'd look good," Chris murmurs.

He turns away, feeling heat rushing up his neck. "You're just saying that," he mumbles.

Chris shifts closer, cupping his face in both hands. "I mean it."

He forces himself to meet Chris' gaze, sees yellow eyes blown dark, hazy. Tanba swallows around the lump in his throat. "Okay."

Chris leans all the way in, pressing their lips together. They're both still a little out of it, and the kiss is almost clumsy, teeth clacking briefly before Chris pulls back. Tanba catches the way his eyes flick down, before he drags them back up. "Can I...?"

Tanba hesitates, jerks his head in a quick nod.

Chris darts in for another quick kiss, and rests his forehead against Tanba's. His knuckles brush against Tanba's jaw, hands smoothing down the length of his neck and over the curve of his collarbones. Chris tracks the strings with his fingers, down to where the top piece flares out. He traces circles over Tanba's chest, teasing brushes over the small nubs of his nipples. Tanba shudders, hard enough to make Chris pause, and he flattens his palms against his chest.

"You're beautiful," Chris whispers.

Tanba squeezes his eyes shut, swallowing the sound that threatens to climb up his throat.

Chris wanders lower, palms fitting over the curve of Tanba's waist. He thumbs at the strings resting over his hipbones, follows it to the back where he squeezes Tanba's ass, making him jump. Fingers hook under the waistband of the bikini, tugging sharply. The gesture has the cloth pulling taut around his ass, and Tanba gasps, grabbing Chris' arms.

"Come here," Chris says.

Tanba looks up just as Chris leans in, catching his lips in another kiss. He tugs again at the bikini, more forceful than before, and Tanba shuffles forward. Chris gives him a moment to settle, and then he tugs him even closer, until their groins are pressed tight together, dragging sharp noises out of them both.

"You," Tanba starts, awed, "You really _do_ like it."

Chris tilts his head back, peeks up from beneath his lashes. "Isn't that what I said?"

He stammers on a nervous laugh. "I guess so."

Chris kisses him again. His touch glides over the small of his back, tracing the knobs of Tanba's spine as he sucks on Tanba's lower lip, slow and lazy.

The touch on his back is more familiar, and Tanba relaxes into it, reaches up to drape his arms over Chris' shoulders. He pushes into the kiss, nudging his tongue past Chris' lips, into the eager heat of Chris' mouth.

By the time Chris' hands start wandering again, there's a low buzz in the base of Tanba's stomach. Palms over his thighs, his hips, fingers brushing against his cock; Tanba whines, feels sparks catching in his nerves.

Chris pulls away, ducking down to fit his lips over the space just below Tanba's jaw. Tanba moans, bares his neck for better access, and feels Chris hums into his skin. He drops lower, tugging at strings with his teeth, nipping at Tanba's collarbone. His mouth wanders, until he's hovering over a nipple, breath blowing warm even through the bikini.

Tanba looks down, catches his gaze.

Chris gives him another smile. Without breaking eye contact, he leans in and licks Tanba's nipple.

He gasps, choking on the sensation. Chris licks him again, and then his lips are closing around his nipple, sucking hungrily. Tanba arches into him, tangles a fist in Chris' hair to pull him closer. He twists in place, dragging their cocks together, and Chris groans like it's been punched out of him.

Chris reaches down to Tanba's crotch, palming the damp spot over his cock. His free hand slides around Tanba's waist, over the bikini, until he's pressing a finger against his hole through the layer of cloth.

Tanba rocks his hips, flushed hot all over from the way Chris is touching him—teasing pressure on one end, long firm strokes on the other, the way he likes it best. Chris' mouth is still working over his nipple, relentless multi-tasker that he is, and it's not long before Tanba is shaking against him, desperate.

Chris pulls back. "Are you close?"

"Yeah," Tanba bites out. "Yeah. Come on."

He shifts his grip, thumbs hard over Tanba's slit.

And just like that Tanba's falling over the edge, spilling into Chris' hand, and soaking the bikini. Chris strokes him a few more times, then wraps his arms over Tanba's waist, anchoring him through the climax.

Tanba comes down panting for breath, blinking spots from his vision. He hears Chris murmuring softly, feels him rub soothing circles into his back.

It isn't until he remembers the hard-on pressed into his crotch that he realises he's barely touched Chris. "Sorry," he says, drawing back. "Kinda left you hanging there."

Chris slants an innocent look his way. "I don't mind," he says, wiping his hand on the sheets. "You'll take care of me now, won't you?"

"Yeah," he says, sliding out of Chris' lap, off the bed, "but not here."

When Chris gives him a confused—and faintly disappointed—look, Tanba chuckles, and grabs Chris' wrist.

"This way," he says.

He leads them out of the bedroom, past the small lounge and out onto the patio. The cold air hits them in full blast, shocks goosebumps all over his skin. Beside him, he feels Chris shiver, and Tanba turns to fold him into an embrace.

Chris melts into him easily, familiar. "Kouichirou," he starts.

Tanba shushes him, urges him forward with an arm around his waist, their feet tapping over the wooden flooring. When they reach the foot of the pool, Chris turns to stare at him.

He disentangles himself from Chris, and takes the first few steps into the pool. The water is warm and cozy, thanks to the in-built heater, and he raises both arms, palm up, towards Chris. "Are you coming?"

Chris takes his hands, follows Tanba deeper in until the water is lapping at their knees.

"Kouichirou," he says again, voice pitched lower than before.

Tanba nods towards the steps. "Sit down."

Comprehension dawns in Chris' expression, and he plonks down faster that Tanba can blink, looking up at him with wide, shining eyes.

Tanba drops to his knees in front of Chris, laughing when Chris spreads his legs eagerly. He dips his hands in the water, leaves a wet trail along the inside of Chris' thigh, up his abdomen. Tanba leans in for a kiss, and Chris' lips part wider on a moan, his fingers curling around his shoulders, pulling him closer. He drags his hands down Chris' chest, catching lightly over his nipples, and pauses as he considers returning the favour.

But Chris pulls back and shoots him a look. "Don't," he warns.

"I haven't even done anything yet," Tanba protests.

When Chris huffs in response, he scoots back, pressing a kiss to Chris' stomach, and starts working his way lower. He hears Chris' breath hitch as he noses at the first curls of hair; Tanba presses a kiss there, then licks him through the cloth, and groans when Chris' cock jolts against his jaw.

He keeps it up until Chris moans, low and wanton, and shoves non-too gently at his shoulder. Chris' cock is straining against the bikini, the tip peeking over the waistband, and that's where Tanba goes. He fits his lips around the head, sucking lightly through the thin cloth. Bracing his weight on one elbow, he uses his free hand to stroke down Chris' length, squeezing the base, and Chris bucks against him hard enough to throw him off.

"Sorry," Chris gasps. Before Tanba can reply, he adds, "Please don't stop."

He grins. "How long have you been planning this?"

"All day," Chris pants. "All day long. I saw that cute two piece in the shop and wanted to see how good you'd looked in it." Here, he hesitates, meeting his gaze. "Wanted you to see if you'd like it on me."

The space in Tanba's ribcage twists with warmth, flutters like a storm of butterflies. "I do," he says.

Chris drops his head back, chest heaving. One hand comes up to make an odd, aborted motion, scattering droplets through the air.

Tanba presses a kiss into his navel, drinks in the soft, vulnerable sound Chris makes.

"Keep going," he pleads.

It takes a bit of angling to keep his nose out of the water, but once he figures it out, Tanba starts sucking Chris off in earnest. He can taste the pre-cum staining the cloth, where the smell of Chris' arousal mixes with the sharp tang of chlorine. Soon enough, Chris is squirming underneath him, his nails scratching hot on Tanba's back.

"That's," Chris tries, choking on the words. "You should—"

Tanba pulls back just enough to speak. "Go ahead," he breathes, feels Chris' cock twitch against his lips. "I'm waiting."

Chris' whole body goes tense, and he comes spurting against Tanba's chin, all over his own stomach. Tanba licks his lips, uses an arm to wipe off the cum dripping down his neck, and doesn't take his eyes off Chris.

He waits until Chris starts to relax, his ragged breathing evening out, before he tugs the bikini all the way down and takes Chris in his mouth.

Chris _yelps,_ hips snapping up as his spine arches. _"T-Too soon,"_ he keens.

Tanba pauses long enough for Chris' nails to dig into his shoulder, grip tightening with every strangled moan he makes, before he moves again. He tongues at the underside of Chris' cock, relishing the way Chris writhes under him, the weight of him filling his mouth, dragging over his lips.

"Kou—" Chris tries again.

Tanba takes him deep, and swallows.

This time, Chris finishes with a shout, splashing hot down Tanba's throat.

Tanba sucks hard, pumping him through the climax as he milks every last bit of cum out of him, until Chris is trembling against him. When Chris finally sags back, boneless and shuddering, Tanba pulls off, licking his lips and grimacing at the taste. He cups some of the pool water in his hands, and uses it to wash away the sticky mess on Chris' abdomen. Then he nuzzles Chris' stomach, sighing as Chris wraps a palm over his nape, caressing his neck. Quiet settles around them, and for a while they lie there, unmoving, catching their breath.

Chris is the first to break the silence; he stirs, chuckling, and murmurs, "Unbelievable."

Tanba peers up at Chris. His eyes are closed, but there's satisfaction nestled in his lips, loose and sweet. Tanba pushes himself up, leaning forward until he can catch that contentment in his mouth.

"So," he says, pulling back, "did that go the way you imagined it?"

Chris' eyelids droop low. "Not exactly," he murmurs, "but it was definitely much better than what I had in mind."

"I'm glad." Tanba brushes a thumb over his cheek, smiles when Chris leans into the touch. "Guess I can change out of this now."

The serene expression on Chris' face twists with disappointment. "Already?"

"It's sticky," he points out. "And wet. And honestly kind of uncomfortable so unless you're planning on a round two, I'm going to take a shower."

"Speaking of round two," Chris starts.

"You are insatiable," Tanba laughs.

Chris' smile crinkles at the corners of his eyes. "Can I join you in the shower?"

"Only if you keep your hands to yourself," Tanba says, knowing from years of experience that Chris won't.

Chris nods. "I promise to do my very best not to touch you until after the shower," he deadpans.

Tanba flicks his nose in retaliation; Chris grins at him, tugs him back down for another kiss.


End file.
